Invasive Mosquito Species in California

Three invasive mosquito species have been detected recently in parts of California. Although the Sutter-Yuba Mosquito and Vector Control District is actively conducting surveillance for these species, they have NOT been found in Sutter or Yuba Counties. Invasive mosquitoes are ones that do not occur here naturally, but come here from other parts of the country or the world. They have come here from Africa, Asia, Australia and the Southern United States.

Asian Tiger Mosquito

Aedes albopictus is a small, dark mosquito with a white stripe behind their head and banded legs. They were first found in El Monte in Los Angeles County in 2011. It has since spread to ten neighboring cities. It has the capability of transmitting Dengue, West Nile Virus, Zika, Chikungunya, Lacrosse and potentially Yellow Fever viruses to humans. They are strongly attracted to humans, but will bite and feed on cats, dogs, and many other mammals.

Yellow Fever Mosquito

Aedes aegypti is a tropical and subtropical mosquito species that is commonly identified by the white lyre shaped markings on its thorax (back). It can be found in many parts of the world and was first detected in California in 2013 in Fresno, Madera, Santa Clara and San Mateo Counties, and was found in Los Angeles County in 2014. As of February 2015, Aedes aegypti have also been found for the first time in San Diego County and in Imperial County near the Mexican border. Most recently, in May of 2015, Aedes aegypti have been found in the city of Hayward in Alameda County. It is capable of transmitting Yellow Fever, Dengue and Chikungunya and Zika viruses to people.

Australian Backyard Mosquito

The third invasive mosquito is called Aedes notoscriptus and is very common in Australia. It was first found in Montebello and Monterey Park in Los Angeles County in 2014. In Australia this mosquito transmits Murray Valley Encephalitis. Much is not know about this mosquito's role in transmitting other mosquito-borne diseases to people, but it is capable of transmitting Dog Heartworm. Aedes aegypti and Aedes albopictus are also capable of transmitting Dog Heartworm. Please remember, these mosquito species have not been found in our area yet, but have the potential to come here at anytime in the future.

Identification for these invasive mosquitoes

Small black and white striped mosquitoes (about 1/4 inch long)

Most likely, they traveled to California as dormant eggs in imported tires, or as eggs, larvae or adult mosquitoes hitch-hiking rides on planes, ships, cars, trucks, shipping containers or other vehicles

They are aggressive day biting mosquitoes

Eggs are laid in ornamental water fountains, potted plants, pet water dishes, or plastic and metal containers in piles of garbage

Even if the mosquito eggs dry out, the eggs can survive for many months and will hatch when coming into contact with water once again

They will breed inside homes or offices in containers of water such as pet dishes, potted plants and saucers and indoor fountains

The eggs of these mosquitoes will look like small black seeds or specks (see photo below)

Yellow Fever, Dengue, Chikungunya and Zika are not locally transmitted in California as of February 2016, but the mosquitoes that can spread these diseases are now found in parts of California. Infected people traveling from other parts of the world could bring these diseases to California. Mosquitoes transmit these diseases to people in a cycle - mosquitoes pick up viruses by biting infected people, then transmit these diseases to other people by biting them. To complete the cycle, these newly infected people can give it back to mosquitoes when they are bitten. In this way, humans are serving as reservoirs (hosts) and invasive mosquitoes are carriers (vectors) of these diseases. Mosquito and vector control districts in the affected areas of California are aggressively trying to control these mosquitoes using a multitude of integrated pest management tools. Methods used to control the eggs, larval, pupal and adult stages are being conducted in these areas.

To stop the spread of these mosquitoes, residents of California need to do their part:

1) Call your local mosquito and vector control district if you see or are bitten by small black and white mosquitoes during the day! They are very sneaky and aggressive, and will easily follow you indoors. Many people will recognize them as something new!

2) Drain and Dump all standing and stagnant water around your home and property. Get rid of any unnecessary items that could hold water. Keep pet dishes, bird baths and kiddy pools scrubbed, clean and fresh. These mosquitoes are capable of laying thousands of eggs in just one container in your yard that holds water! They commonly lay their eggs in saucers placed under potted plants (fill saucers with sand), clogged rain gutters, standing water under houses, rain barrels and buckets, around leaky faucets, abandoned swimming pools and hot tubs, ornamental ponds, fish ponds, unsealed septic tanks and even trash piles. Keep your windows and doors properly screened.

4) Do Not Transport or share plant stems that have been rooted in water, as these containers could be contaminated with mosquito eggs - example: lucky bamboo. Do not transport potted plants and the saucers used with them as these may also be contaminated with mosquito eggs.

As of September 2017, none of these invasive mosquitoes have been found in Sutter or Yuba Counties. However, if you see any mosquitoes fitting the above description, please call the Sutter-Yuba Mosquito and Vector Control District immediately at 530-674-5456. Once established, these mosquitoes are very difficult if not impossible to eradicate and control, but early detection might make it possible.